Simulation of acute subdural hematoma and diffuse axonal injury in coronal head impact.

Coronal head impacts were simulated in a physical model, based on the hypothesis that acute subdural hematoma (ASDH) is related to cerebral vertex displacement and diffuse axonal injury (DAI) to local Green-Lagrange strain. The geometry of the 2D model was based on anatomical measurements taken from the MRI scans of 10 adult males. Silicone gel modelled the cerebrum, paraffin the CSF and elastic membranes the trabeculae of the sulci. Pendulum impacts gave peak angular acceleration of 7800 rad s(-2) in models with and without sulci. The motion of the gel and Green-Lagrange strain were calculated from tracked coordinates of Patrick markers. Worst-case bridging vein strains are produced on the contrecoup side and are approximately doubled by adding sulci. Given that axons in the corpus callosum are highly oriented, Green-Lagrange strain was resolved in the fibre direction. It is found to be close to the minimum principal strain, indicating a degree of natural, teleological protection for the axons. The data support the use of delta0peak as a suitable descriptor for the risk of DAI but not for ASDH.